Pulse generating circuit arrangment for producing pulses of different adjustable durations

ABSTRACT

A pulse generating circuit arrangement comprises a sawtooth generator. The sawtooth generator comprises an adjustable potentiometer connected in series with a capacitor. The input of a potentiometer comprising an adjustable potentiometer connected in series with a voltage divider is connected to the output of the sawtooth generator. The inputs of a threshold switch circuit are connected to the outputs of the potentiometer. The threshold switch circuit comprises a plurality of transistors having emitter electrodes connected to a zero voltage line, base electrodes connected to the outputs of the potentiometer and collector electrodes connected to the corresponding ones of a plurality of outputs and to a source of operating voltage via corresponding ones of a plurality of resistors. The sawtooth generator and potentiometer control the threshold switch circuit to produce at the outputs of said circuit a plurality of output circuits having coincident leading edges and different durations. The adjustable potentiometer of the sawtooth generator controls the duration of the output pulse having a maximum duration provided at one of the outputs of the threshold switch circuit. The adjustable potentiometer of the potentiometer controls the duration of the output pulse having a minimum duration provided at another of the outputs of the threshold switch circuit and the voltage divider of the potentiometer controls the durations of the output pulses having intermediate durations provided at others of the outputs of the threshold switch circuit.

United States Patent [72] Inventor Heinz Luczkowski Bielefeld, Germany[21] Appl. No. 624,899 [22] Filed Mar. 21, 1967 [45] Patented Jan. 12,1971 [73] Assignee Anker-Werke Aktiengesellschaft Bielel'eld, Germany acorporation of Germany [32] Priority Mar. 24, 1966 [33] Germany [31] No.A 51,946

[54] PULSE GENERATING CIRCUIT ARRANGMENT FOR PRODUCING PULSES OFDIFFERENT ADJUSTABLE DURATIONS 10 Claims, 5 Drawing Figs.

[52] US. Cl 307/265, 307/228, 307/235, 328/58, 328/112, 328/116, 328/ l80 [51] Int. Cl [103k 1/18 [50] Field of Search 307/228, 235, 244, 265;328/36, 58, 62,1ll112, 105--106,150,153,180,115,116;315/26 [56]References Cited UNITED STATES PATENTS 2,954,502 9/ 1960 Carpenter etal. 307/228X 3,257,567 6/1966 Kotas 328/183X 3,300,655 l/1967 Rosenbluth328/183X 3,395,293 7/1968 Perloff 328/183X SAWTO0TH P GENERATOR] SE/SPrimary Examiner-Stanley D. Miller Att0meys-Curt M. Avery, Arthur E.Wilfond, Herbert L.

Lerner and Daniel J. Tick ABSTRACT: A pulse generating circuitarrangement comprises a sawtooth generator. The sawtooth generatorcomprises an adjustable potentiometer connected in series with acapacitor. The input of a potentiometer comprising an adjustablepotentiometer connected in series with a voltage divider is connected tothe output of the sawtooth generator. The inputs of a threshold switchcircuit are connected to the outputs of the potentiometer. The thresholdswitch circuit comprises a plurality of transistors having emitterelectrodes connected to a zero voltage line, base electrodes connectedto the outputs of the potentiometer and collector electrodes connectedto the corresponding ones of a plurality of outputs and to a source ofoperating voltage via corresponding ones of a plurality of resistors.The sawtooth generator and potentiome' ter control the threshold switchcircuit to produce at the outputs of said circuit a plurality of outputcircuits having coincident leading edges and different durations. Theadjustable potentiometer of the sawtooth generator controls the durationof the output pulse having a maximum duration provided at one of theoutputs of the threshold switch circuit. The adjustable potentiometer ofthe potentiometer controls the duration of the output pulse having aminimum duration provided at another of the outputs of the thresholdswitch circuit and the voltage divider of the potentiometer controls thedurations of the output pulses having intermediate durations provided atothers of the outputs of the threshold switch circuit.

| THRESHOLD SWITCH CIRCUIT 3 l PULSE GENERATING CIRCUIT ARRANGMENT FORPRDDUCING PULSES OF DIFFERENT ADJUSTABLE DURATIONS DESCRIPTION OF THEINVENTION The present invention relates to a pulse generating circuitarrangement. More particularly, the invention relates to a pulsegenerating circuit arrangement for producing pulses of differentadjustable durations.

German Pat. No. 1,037,508 discloses an arrangement for producing twooutput pulses by means of an input pulse, whereby the second outputpulse is delayed relative to the first output pulse. The arrangementcomprises a transformer having a primary winding connected to the pulsegenerator and a secondary winding in which the leading edge of theprimary pulse produces a first pulseand the trailing edge of saidprimary pulse produces a time-delayed second pulse, of oppositepolarity. Two load circuits are connected in series with the secondarywinding of the transformer and an electron tube is connected in parallelwith such load circuits. The electron tube responds to the polarity ofthe pulses in the secondary winding. In accordance with the polarity ofthe pulses in the circuit of the secondary winding the electron tubeshort-circuits the load circuit in a manner whereby a first pulse may bederived from one load circuit and a second pulse, which is time-delayedrelative to the first pulse, may be derived from the other load circuit.This arrangement is not suitable for the production of more than twotime-delayed output pulses.

German Pat. No. l,038,l ll utilizes an oscillator to produce pulsesequences with adjustable pulse durations and pulse spacing. Theoscillator produces pulses for a counter which controls by dischargepulses a bistable multivibrator or flipflop. The flip-flop circuitproduces a defined sequence of pulses as well as an adjustable width anda determinable time interval. The pulse sequence simultaneously servesto control an oscillator via another counter and a pulse circuit whichdetermines the time interval of the produced pulses. This circuitarrangement cannot, however, produce pulses having the same leading edgeand duration which may be staggered, relative to the time. I

tiometer, has an input connected to the output of the sawtooth generatorand outputs. A threshold switch circuit has inputs connected to the ofof the potentiometer and outputs. The threshold switch circuit producesat the outputs under the control of the sawtooth generator and thepotentiometer a plurality of output pulses having coincident leadingedges and different durations. The sawtooth generator comprisesadjustable constant current means and a capacitor connected in serieswith the constant current means. The output of the sawtooth generatorand the input of the potentiometer are connected to the capacitor. Theadjustable constant current means comprises an adjustable potentiometerfor controlling the duration of the output pulse having a maximumduration provided at one of the outputs pulse having a maximum durationprovided at one of the outputs of the threshold switch circuit. Thepotentiometer comprises an adjustable potentiometer and a voltagedivider connected in series with the adjustable potentiometer. Theadjustable potentiometer controls the duration of the output pulsehaving a minimum duration provided at one of the outputs of thethreshold switch circuit. The voltage divider of the potentiometercomprises a plurality of resistors having electrical resistances indeterminedpropor- I tions to each other. The voltage divider controlsthe durations Monostable multivibrators, connected in parallel or inseries, have been developed as pulse delay circuits. The pulse delaycircuits produce output pulses of the aforementioned type in accordancewith an input pulse. The disadvantage of the monostable multivibratorcircuit is that the time for each monostable multivibrator stage must beadjusted individually. In the case of parallel connected monostablemultivibrator stages which provide pulses of approximately equalduration, variations in pulse duration due to temperature variationscaused by the spatial arrangement of the circuit, and due to variationsin the transistors, may disrupt the sequence of the pulses.

Although the sequence of 'pulses is not disrupted in monostablemultivibrator stages which are connected in series, the monostablemultivibrator stages must be logically connected to each other and theproduced output pulses are interrupted for short periods at theswitching points.

The principal object of the present invention is to provide a new andimproved pulse generating circuit arrangement. An object of the presentinvention is to provide a pulse generating circuit arrangement whichovercomes the disadvantages of the pulse generating circuit arrangementsof known type, and specifically those which produce output pulses havingthe same leading edge and different durations. The pulse generatingcircuit of the present invention'is of simple structure, is readily andfacilely adjustable, is effective, efficient and reliable in operationand produces pulses having coincident leading edges and differentdurations.

In accordance with the present invention, a pulse generating circuitarrangement comprises a sawtooth generator having an input and anoutput. An input applies an input pulse to the input of the sawtoothgenerator for controlling the operation thereof. A potential shifter,hereinafter briefly called potenof the output pulses having intermediatedurations provided at others of the outputs of the threshold switchcircuit. The threshold switch circuit comprises a plurality oftransistors each having emitter, collector and base electrodes. The baseelectrodes of the transistors are connected to the outputs of thepotentiometer. The emitter electrodes of the transistors are connectedto a zero voltage line and the collector electrodes of the transistorsare connected to the corresponding outputs of the threshold switchcircuit and to a source of operating voltage via corresponding ones of aplurality of resistors. The threshold switch circuit further comprises aplu rality of switching accelerating circuits each connected to acorresponding one of the plurality of transistors.

In order that the present invention may be readily carried into effect,it will now be described with reference to the accompanying drawings,wherein: 7

FIG. 1 is a block diagram of an embodiment of the pulse generatingcircuit arrangement of the present invention;

FIG. 2 is a circuit diagram of the embodiment of FIG. I of the presentinvention;

FIG. 3 is a graphical presentation the circuit of FIG. 2;

FIG. 4 is a graphical presentation of the output pulses produced by thepulse generating circuit arrangement of the present invention; and

FIG. 5 is a circuit diagram of a modified part of the circuit of FIG. 2.

As shown in FIG. 1, the pulse generating circuit arrangement of thepresent invention comprises a sawtooth generator 1, a potentiometer 2and a threshold switch circuit 3. The threshold switch circuit 3comprises a plurality of threshold switches 8,, S S and 8,, havingcorresponding outputs A A,, A and A,.

As shown in FIG. 2, the sawtooth generator 1 comprises an input lead 30connected to a pulse generating or timer circuit. The lead 3a isconnected via a resistor 4 to a lead 5 via which the supply voltage U,is applied to the circuit. A lead 6 connects the lead 3a to the baseelectrode of a PNP transistor 7. The emitter electrode 8 of thetransistor 7 is connected to the lead 5 and the collector electrode 9 ofsaid transistor is connected to a resistor 10.

The resistor 10 is connected to a capacitor 12 via a lead 11. Thecapacitor 12 is also connected to the lead 5. A first terminal a isconnected to one plate of the capacitor 12 and a second terminal 12 isconnected to the other plate of said capacitor. The terminals a and bare utilized to measure the voltage across the capacitor 12. The lead 11is connected to the collector electrode T3 of a PNP transistor 14. Theemitter electrode 15 is connected to a potentiometer 16 which adjuststhe current J. The potentiometer 16 is connected to a lead 17 of voltageversus time in via which the supply voltage U is applied to the circuit.The

base electrode 18 of the transistor 14 is connected to a lead l) inwhich resistors Eli and 21 are connected. The resistor Zll is connectedto the lead 117 via a lead 22 and the resistor 21 is connected to a zerovoltage lead 24 having a zero voltage U via a lead 23. The output lead2442 is connected to the lead l )1.

As shown in EEG 2, the potentiometer 2 comprises a resistor connected tothe lead T7. The resistor 25 is connected to the base electrode 27 of anNPN transistor 23 via a lead 26 and to a resistor 29 via said lead. Theresistor 29 is connected to the lead 24 via the lead 30. The emitterelectrode 331 of the transistor 28 is connected to an adjustablepotentiometer 32, which is connected to the lead 317 by a lead 33. Thecollector electrode 34 of the transistor 2% is connected to a resistor35 and to a resistor 37 via a lead as.

The resistor 35 is connected to a resistor 39 via a lead 38 and to aresistor 41 via a lead 40. The resistor 39 is connected to a resistor 43via a lead 42 and to a resistor d5 via a lead 44. The resistor 33 isconnected to the emitter electrode 47 of an NPN transistor 48 via a lead46. The base electrode 49 of the transistor 48 is connected to the leadll via the lead 244 which serves as the input of the potentiometer 2 aswell as the output of the sawtooth generator 1. The collector electrode50 of the transistor 48 is connected to the lead 5. The resistor 43 isconnected to a resistor 52 via a lead 51. The leads 53, 54, 5S and 56,connected to the resistors 37, 41, 45 and 52, respectively, are theoutputs of the potentiometer 2.

The leads S3, 54, 55 and 56 also function as the inputs of the thresholdswitch circuit 3. The lead 53 connects the resistor 3? to the baseelectrode 57 of a PNP transistor 61. The lead 54 connects the resistor41 to the base electrode 53 of a PM? transistor 62. The lead 55 connectsthe resistor 45 to the base electrode 5% of a PNP transitor 63. The lead56 connects the resistor 52 to the base electrode so of a PNP transistor64. Each of the emitter electrodes 65, 66, 67 and 68 of the transistors6T, 62, E53 and 64, respectively, is connected to the lead 24. Thecollector electrode 69 of the transistor 61 is connected to the lead l7via a lead 73, a resistor 77 and and a lead The collector elec rode 7i?of the transistor 62 is connected to the lead ll? via lead 74, aresistor 78 and a lead 82. The collector electrode 711 of the transistor63 is connected to the lead 17 via a lead 75, a resistor 79 and a lead33. The collector electrode 72 of the transistor 64 is connected to thelead 17 via a lead 76, a resistor fill and a lead 34). The outputterminal A, is connected to the lead 73 via a lead 85. The outputterminal A is connected to the lead 7d via a lead 86. The outputterminal A is connected to the lead 75 via a lead 87. The outputterminal A, is connected to the lead 76 via a lead 88.

ETC. 3 illustrates the voltage as a function of time. Thus U :(t), whereU is the voltage and t is the time. The resistors 35, 39 and 43 of H6. 2are assumed, in this case, to have equal electrical resistances. in HQ.3, the abscissa represents time t and the ordinate represents voltage U.if the resistances of the resistors 35, 39 and 43 are equal, theintervals between the times T and T T and T T and T are equal.

HG. 4 illustrates the output pulses at the output terminals A A: A andA, when the resistances of the resistors 35, 39

43 are not equal. Each of the output pulses at T T T and T, has aleading edge which is coincident with those of the others and with thatof the trigger pulse supplied to the input of the sawtooth generator llvia the lead 3a and each of said output pulses ha a difierent durationso that each 30 said output pulses has a trailing edge which occurs at atime different from the occurence of the others.

in operation, an input or trigger pulse is supplied to the circult ofP56. 2 via the input lead 301 the input pulse permits the discharge ofthe capacitor l2 via the transistor 7. Upon the tel. .ination of theinput pulse, the transistor 7 is again switched to its nonconductivecondition. The transistor 14 is connected as an adjustable constantcurrent source which permits the charging of the capacitor 12, so thatthe voltage of said capacitor rises linearly with time. The resultantsawtooth voltage is applied to the potentiometer 2, and morespecifically to the transistor 438. The transistordil functions as anemitter follower and its output voltage is applied to a voltage dividercomprising the resistors 35, 39 and 43 and the transistor 28. Thetransistor 28 is connected as a current generator. in this manner,additionalsawtooth voltages, displaced by defined potentials, occur atthe voltage divider and are applied to the base electrodes 57, 59 andtill, respectively, of the transistors til, s2, 63 and 64, respectively.

The transistors 61, 62, 63 and 64 function as threshold switches. whenthe potential at the base electrode of a transistor ol to ti lreachesthe threshold voltage U,,, such transistor is switched to its conductivecondition. When a transistor oil to at is in its conductive condition,it changes the potential at its corresponding output terminal A A A orA, from U to zero volts. The threshold voltages U, are determined by thevoltage of the sawtooth generator 1 and the potential differences of thevoltage divider. Since this is a linear time function, the constantdisplacement of the potential of the voltage divider is also a definedtime displacement.

The ratio of the electrical resistances of the resistors 35, 39 and 43of the voltage divider is in proportion to the displacement ofpotential, and is thus also in proportion to the timestaggered outputpulses provided at the output terminals A, to

The pulse duration T (T,,) of the output pulse of the maximum durationprovided at the output terminal A (A,,) is varied, controlled oradjusted by variation of the potentiometer 16. The pulse duration T ofthe output pulse of minimum duration provided at the output terminal A,is varied, controlled or adjusted by the potentiometer 32. The pulsedurations T and T of the output pulses of intermediate duration providedat the output terminals A and A are varied, controlled or adjusted inaccordance with the resistance ratio of the resistors 35, 3) and 43.

The duration T. is determined with adequate exactness by neglecting thecollector-saturation voltage of the transistor 7 as well as thebase-emitter voltages of the transistors 48 and 54-. The transistor 64is switched to its conductive condition when the voltage at thecapacitor l2 becomes negative relative the threshold voltage U Therequired loading Q of the capacitor 112 results from the generalrelation:

in the foregoing relation, if C is the capacitance in microfarads, U isthe voltage in volts and i is the current in milliamperes, t is the timein milliseconds. if i .l a constant and i=1}, the pulse duration T inmilliseconds is For all other pulse durations,

U R .5 U,

where U is the threshold voltage, U is the voltage of the capacitor 12and J is the current which is variable under the control of thepotentiometer 32.

Although the pulse generating circuit arrangement of HG. 2 is describedas having four outputs, it may have any suitable number n of outputs.The pulse generating circuit arrangement of the present inventionreadily replaces the monostable multiviorators of the prior art. Aprimary advantage of the pulse generating circuit arrangement of thepresent invention over the prior art circuits is that the adjustment ofthe duration of the longest and short pulses automatically adjust theintermediate pulses to a predetermined level. The pulse generatingcircuit arrangement of the present invention may be utilized to controlsequential processes such as, for example, machine control processes thelike.

The switching of the transistors all to 61 (MG. 2) may be considerablyaccelerated by the accelerating circuit of H6. 5 in order to provide asteep rise or slope in the sawtooth voltage. The accelerating circuit ofFIG. 5 is shown only for one of the transistors 64; actually eachtransistor should be connected to a corresponding accelerating circuit.

ln FIG. 5, the primary winding to of a transformer T is connected in alead 76 between the collector electrode in of the transistor 64 and theresistor 80. One end of the secondary winding M of the 5 is shown onlyfor one of the transistors 64; actually each transistor should beconnected to a corresponding accelerating circuit. between the baseelectrode 60 of the transistor 64 and the resistor 52. The other end ofthe primary winding 90 is connected to the lead 24 via 'a lead 92. Adiode 96 is connected to the lead 88 via a lead 95 and is connected tothe lead 76 via a lead 97. The diode 96 is connected to a point on thelead 76 between the primary winding 90 and the resistor 80.

When the sawtooth voltage switches the transistor 64 to its conductivecondition, an output voltage is provided at the secondary winding 91 ofthe transformer T. Since the negative pole of the secondary winding 91is connected to the base electrode 60 of the transistor 64, via the lead93, the diode 94 and the lead 56, the voltage applied to said baseelectrode accelerates theswitching of the transistor 64 to itsconductive condition.

While the invention has been described by means of a specific exampleand in a specific embodiment, I do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

1. A pulse generating circuit arrangement comprising:

, sawtooth generating means having an input and an output;

input means for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof; potentiometermeans having an input connected to the output of said sawtoothgenerating means and outputs; and threshold switching means havinginputs connected to the outputs of said potentiometer means and outputsfor producing at said outputs under the control of said saw-, toothgenerating means and said potentiometer means a plurality of outputpulses having coincident leading edges and different variable durationsof the maximum and minimum output pulses, said sawtooth generating meanscontrolling the duration of the output pulse having a maximum durationprovided at one of the outputs of said threshold switching means. i

2. A pulse generating circuit arrangement asclaimed in claim 1, whereinsaid sawtooth generating means comprises adjustable constant currentmeans and a capacitor connected in series circuit arrangement with saidconstant current means, the output of said sawtooth generating meansbeing connected to a common point in the connection between saidconstant current means and said capacitor.

3. A pulse generating circuit arrangement as claimed in claim 1, whereinsaid potentiometer means comprises an adjustable potentiometer andvoltage divider means connected in series with said adjustablepotentiometer, said adjustable potentiometer controlling the duration ofthe output pulse having a minimum duration provided at one of theoutputs of said threshold switching means.

4. A pulse generating circuit arrangement comprising:

sawtooth generating means having an input and an output,

said sawtooth generating means comprising a first ad justablepotentiometer for controlling the duration of the output pulse;

input means for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof;

potentiometer means having an input connected to the output of saidsawtooth generating means and outputs, wherein said potentiometer meanscomprises a second adjustable potentiometer and voltage divider meansconnected in series with said second adjustable potentiometer, saidsecond adjustable potentiometer controlling the duration of the outputpulse having a minimum duration provided at another of the outputs ofsaid threshold switching means; and

threshold switching means having inputs connected to the outputs of saidpotentiometer means and outputs for producing at said outputs under thecontrol of said sawtooth generating means and said potentiometer means aplurality of output pulses having coincident leading edges and differentdurations, the output pulse having a maximum duration provided at one ofthe outputs of said threshold switching means.

5. A pulse generating circuit arrangement as claimed in claim 4, whereinthe voltage divider means of said potentiometer means comprises aplurality of resistors having electrical resistances in determinedproportions to each other, said voltage divider means controlling thedurations of the output pulses having intermediate durations provided atothers of the outputs of said threshold switching means.

6. A pulse generating circuit arrangement as claimed in claim 4, whereinsaid threshold switching means comprises a plurality of transistors eachhaving emitter, collector and base electrodes, connecting meansconnecting the base electrodes of said transistors to the voltagedivider means of said potentiometer means, a zero voltage line,additional connecting means connecting the emitter electrodes of saidtransistors to said zero voltage line, a source of operating voltage, aplurality of resistors and further connecting means connecting thecollector electrodes of said transistors to the corresponding outputs ofsaid threshold switching means and to said source of operating voltagevia corresponding ones of said plurality of resistors.

7. A pulse generating circuit arrangement as claimed in claim 6, whereinsaid threshold switching means further comprises a plurality ofswitching accelerating circuits each connected to a corresponding one ofsaid plurality of transistors.

8. A pulse generating circuit arrangement comprising:

sawtooth generating means having an input and an output;

input means for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof;

potentiometer means having an input connected to the output of saidsawtooth generating means and outputs; and

threshold switching means having inputs connected to the outputs of saidpotentiometer means and outputs for producing at said outputs under thecontrol of said sawtooth generating means and said potentiometer means aplurality of output pulses having coincident leading edges and differentdurations, said threshold switching means comprising a plurality oftransistors each having emitter, collector and base electrodes,connecting means connecting the base electrodes of said transistors tothe outputs of said potentiometer means, a zero voltage line, a sourceof operating voltage, a plurality of resistors, additional connectingmeans connecting the emitter electrodes of said transistors to said zerovoltage line and further connecting means connecting the collectorelectrodes of said transistors to the corresponding outputs of saidthreshold switching means and to said source of operating voltage viacorresponding ones of said plurality of resistors.

9. A pulse generating circuit arrangement as claimed in claim 8, whereinsaid threshold switching means further comprises a plurality ofswitching accelerating circuits each connected to a corresponding one ofsaid plurality of transistors.

10. A pulse generating circuit arrangement comprising:

sawtooth generating means having an input and an output,

said sawtooth generating means comprising adjustable constant currentmeans and a capacitor connected in series circuit arrangement with saidconstant current means:

input means for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof;

means of said sawtooth generating means comprising an adjustablepotentiometer for controlling the duration of the output pulse having amaximum duration provided at one of the outputs of said thresholdswitching means; and the output of said sawtooth generating meansv beingconnected to a common point in the connection between said constantcurrent means and said capacitor.

1. A pulse generating circuit arrangement comprising: sawtoothgenerating means having an input and an output; input means for applyingan input pulse to the input of said sawtooth generating means forcontrolling the operation thereof; potentiometer means having an inputconnected to the output of said sawtooth generating means and outputs;and threshold switching means having inputs connected to the outputs ofsaid potentiometer means and outputs for producing at said outputs underthe control of said sawtooth generating means and said potentiometermeans a plurality of output pulses having coincident leading edges anddifferent variable durations of the maximum and minimum output pulses,said sawtooth generating means controlling the duration of the outputpulse having a maximum duration provided at one of the outputs of saidthreshold switching means.
 2. A pulse generating circuit arrangement asclaimed in claim 1, wherein said sawtooth generating means comprisesadjustable constant current means and a capacitor connected in seriescircuit arrangement with said constant current means, the output of saidsawtooth generating means being connected to a common point in theconnection between said constant current means and said capacitor.
 3. Apulse generating circuit arrangement as claimed in claim 1, wherein saidpotentiometer means comprises an adjustable potentiometer and voltagedivider means connected in series with said adjustable potentiometer,said adjustable potentiometer controlling the duration of the outputpulse having a minimum duration provided at one of the outputs of saidthreshold switching means.
 4. A pulse generating circuit arrangementcomprising: sawtooth generating means having an input and an output,said sawtooth generating means comprising a first adjustablepotentiometer for controlling the duration of the output pulse; inputmeans for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof; potentiometermeans having an input connected to the output of said sawtoothgenerating means and outputs, wherein said potentiometer means comprisesa second adjustable potentiometer and voltage divider means connected inseries with said second adjustable potentiometer, said second adjustablepotentiometer controlling the duration of the output pulse having aminimum duration provided at another of the outputs of said thresholdswitching means; and threshold switching means having inputs connectedto the outputs of said potentiometer means and outputs for producing atsaid outputs under the control of said sawtooth generating means andsaid potentiometer means a plurality of output pulses having coincidentleading edges and different durations, the output pulse having a maximumduration provided at one of the outputs of said threshold switchingmeans.
 5. A pulse generating circuit arrangement as claimed in claim 4,wherein the voltage divider means of said potentiometer means comprisesa plurality of resistors having electrical resistances in determinedproportions to each other, said voltage divider means controlling thedurations of the output pulses having intermediate durations provided atothers of the outputs of said threshold switching means.
 6. A pulsegenerating circuit arrangement as claimed in claim 4, wherein saidthreshold switching means comprises a plurality of transistors eachhaving emitter, collector and base electrodes, connecting meansconnecting the base electrodes of said transistors to the voltagedivider means of said potentiometer means, a zero voltage line,additional connecting means connecting the emitter electrodes of saidtransistors to said zero voltage line, a source of operating voltage, aplurality of resistors and further connecting means connecting thecollector electrodes of said transistors to the corresponding outputs ofsaid threshold switching means and to said source of operating voltagevia corresponding ones of said plurality of resistors.
 7. A pulsegenerating circuit arrangement as claimed in claim 6, wherein saidthreshold switching means further comprises a plurality of switchingaccelerating circuits each connected to a corresponding one of saidplurality of transistors.
 8. A pulse generating circuit arrangementcomprising: sawtooth generating means having an input and an output;input means for applying an input pulse to the input of said sawtoothgenerating means for controlling the operation thereof; potentiometermeans having an input connected to the output of said sawtoothgenerating means and outputs; and threshold switching means havinginputs connected to the outputs of said potentiometer means and outputsfor producing at said outputs under the control of said sawtoothgenerating means and said potentiometer means a plurality of outputpulses having coincident leading edges and different durations, saidthreshold switching means comprising a plurality of transistors eachhaving emitter, collector and base electrodes, connecting meansconnecting the base electrodes of said transistors to the outputs ofsaid potentiometer means, a zero voltage line, a source of operatingvoltage, a plurality of resistors, additional connecting meansconnecting the emitter electrodes of said transistors to said zerovoltage line and further connecting means connecting the collectorelectrodes of said transistors to the corresponding outputs of saidthreshold switching means and to said source of operating voltage viacorresponding ones of said plurality of resistors.
 9. A pulse generatingcircuit arrangement as claimed in claim 8, wherein said thresholdswitching means further comprises a plurality of switching acceleratingcircuits each connected to a corresponding one of said plurality oftransistors.
 10. A pulse generating circuit arrangement comprising:sawtooth generating means having an input and an output, said sawtoothgenerating means comprising adjustable constant current means and acapacitor connected in series circuit arrangement with said constantcurrent means: input means for applying an input pulse to the input ofsaid sawtooth generating means for controlling the operation thereof;potentiometer means having an input connected to the output of saidsawtooth generating means and outputs; threshold switching means havinginputs connected to the outputs of the said potentiometer means andoutputs for producing at said outputs under the control of said sawtoothgenerating means and said potentiometer means a plurality of outputpulses having coincident leading edges and different durations, theadjustable constant current means of said sawtooth generating meanscomprising an adjustable potentiometer for controlling the duration ofthe output pulse having a maximum duration provided at one of theoutputs of said threshold switching means; and the output of saidsawtooth generating means being connected to a common point in theconnection between said constant current means and said capacitor.